Locks are often sold with the claimed advantage of their keys being impossible to legally copy without manufacturer authorization:

The key is two-sided, with US patent no. 8,336,350. Benefits of the LOCXIS cylinder, by RB-LOCKS: Patented until 2030

And another example of such advertising:

Patent-protected key systems ensure that no one other than the provider – or a third party appointed by the provider – can produce keys or key blanks. Attempting to copy patent-protected keys have consequences not unlike violating copyright laws. Duplicating a patent-protected key without expressed permission of the owner or organization can face severe financial penalties

But is there actual case law that supports the manufacturers legal theory? To me it seems odd that a patent on a lock system would be sufficient to forbid making copies of the keys, rather than of the lock itself.

  • 1
    Why do you assume the key design isn’t also patented?
    – Eric S
    Jul 30, 2020 at 13:23
  • @EricShain the keys themselves are usually fairly simple compared to the lock mechanism. It's unlikely they could be patented on their own. Jul 30, 2020 at 13:56
  • 1
    @JonathanReez: Generally a patent will cover all new novel parts of a system. In the example provided, it appears that there are "divots" on the side of the key, outside of the normal key groove. These are probably "novel"(from a patent examiner's perspective, if key patents are like software patents) extensions on the prior art of keys. Alternatively, the patent may cover the machinery necessary to create these specific divots in a way that the lock would accept.
    – sharur
    Jul 30, 2020 at 15:03
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    Dimple locks are around since at least the 1976 DOM patent. While out of patent, unlicensed locksmiths can't obtain keyblanks and tooling.
    – Trish
    Jul 30, 2020 at 17:31
  • 1
    @Trish wouldn't they be able to get them made by a machine shop or similar? Sure, probably more expensive than just buying mass-produced blanks, but certainly not phenomenally expensive. Jul 30, 2020 at 21:09

1 Answer 1


Locks are tricky. As the LPL will tell you, half the security a lock offers is in having a good keyway. The more obscure, the more secure it can be. Like the LPL's 10 nastiest. But while picking is one way to open a door that needs skill and training and in some states a license as a locksmith, the good old-fashioned way is to get a key. But how do companies make sure not everybody gets their hands on blanks and the tooling to make afterkeys to make these devices somewhat secure?!

While the patent for exampe the Dimple Lock was given out in 1975/1976 to DOM the key part in controlling the making after keys is obtaining the key blanks.

Keys are usually patentee as a package together with the lock they belong to: a key alone can not do anything, a lock without a key doesn't open, the two need t be designed and work together. Making afterkeys is just the same as making faked locks, as long as the patent runs (as long as it's a valid one!) But what if the patent runs out? That's when the Trademarks come into play. For example Abus owns the Trademark SmartX (79246136), which is trademarked among others in the category:

IC 006. US 002 012 013 014 023 025 050. G & S: locks of metal, keys of metal for locks, metal key holders, metal key blanks

Yes, USPTO allows to trademark the shape and style of key blanks, at least the non-functional parts of them. The special shape of a key can after all be an identifier of the source of a product. And indeed, two of the non-named marks Abus owns are 79234697 & 79236119 - the literal crosssection of two of their keys! This could make it virtually impossible to make replacement keys without incurring liability for at least a trademark violation if you can manage to get into the extremely tight tolerances (because of which there are only a few companies that do it and only for very popular keys).

At least that's what the Key manufacturers want. Caselaw is a little more tricky and tells us, that at least Best Universal Lock Co has had no easy game so far:

Falcon Locks Co v Best Universal Lock Co seems utterly confusing: Best won on the unfair competition part, but also lost in that Falcon could make lock housings for the patented Best lock...

Best Universal Locks v ILCO Unican Corp held in 1993 that the patent of Best was invalid because of prior art and that the '636 "design patent was invalid because the shape of the blank key blade was dictated by its function." That patent has the full key blade though, and the crosssection is not necessarily a part of the function, while the rest of the key blade is functional.

The two Abus trademarks on the aesthetic of the keyway to denote these are Abus made locks might or might not stand over time, but so far they are valid.

  • The USPTO links don't seem to work Jul 30, 2020 at 22:28
  • Also, you can trademark the shape of a key blank? Is that also the case for EU countries or is their patent office just as insane? Jul 30, 2020 at 22:29
  • @JonathanReez if it is not functional, yes. Fixed the USPTO links and added the Vest v Ilco case's patent drawing
    – Trish
    Jul 30, 2020 at 22:46
  • The first USPTO link still doesn't work for me. And I don't see a link to the drawing? Jul 30, 2020 at 22:48
  • @JonathanReez '636 , the SmartX trademark is Serial 79246136
    – Trish
    Jul 30, 2020 at 22:51

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